Early osseointegration of strontium-doped coatings on titanium implants in an osteoporotic rat model

Abstract

Osteoporosis is a skeletal disorder characterized by a decrease in bone strength leading to a higher risk of fracture. In this scenario, many osteoporotic patients require permanent prosthesis. Surface modification is a strategy to improve the osseointegration for cementless implants. This work assesses the in vivo performance of a surface modification consisting in a bioactive silica-based layer with strontium-doped bioactive glass particles. The layer was made by sol-gel and applied onto titanium nail-shaped implants. Osseointegration tests were performed on an osteoporotic rat model generated by ovariectomization. The effectiveness of the osteoporotic rat model was systematically analyzed for structure and bone quality using classic and novel techniques: nanoindentation, micro-Raman spectroscopy and digital image processing. It was found that Sr- glass coatings applied on nail-shaped implants result with lower numbers of particles than for plane samples. The positive effect of bioactive Sr-glass coatings on the new bone tissue formation was evident from the results of the Raman tests. Besides, histomorphometric results showed that the newly formed bone thicknesses around coated Sr-bioactive implants are 15% larger than those formed around titanium materials 15 and 30 days after implantation. These results indicated that even when the nail-shaped implants have a relative low number of bioactive Sr-glass particles, they have a positive effect to induce the formation of new bone. Further research is needed to find the means to increase the number of particles in the coating, while tests at longer times are necessary to investigate the period of effectiveness.